1. Technical Field
This disclosure is generally related to solid-state lamps such as luminaires.
2. Description of the Related Art
Lighting designers and installers often need to adjust an output intensity of a lighting device (e.g., luminaire) that has been installed. In particular, it may be desirable to adjust the output intensity of one or a few lighting devices within a track or from an entire floor of lighting without affecting the remaining lighting devices. For example, after the installation of multiple lighting devices at a shopping area, brighter lighting may be desired near stairways, escalators, entrances, or rest rooms, while dimmer lighting may be desired near store-fronts, self-illuminated displays, kiosks, or above well-lit seasonal displays, such as above Christmas trees.
Many lighting devices are installed at heights that cause adjustment of lighting devices, e.g., changing light bulbs, to be time-consuming and costly. In many situations, the lighting devices are mounted at heights exceeding the reach of a maintenance person, even while on a ladder. As a result, adjusting the lighting devices requires a “bucket truck” or a self-propelled scissor lift. Use of such equipment requires following safety procedures, such as blocking off the work area and posting an additional worker to stand as a look-out, to protect both the maintenance person and any potential customers in the vicinity of the maintenance. Thus, adjusting lighting devices can be time-consuming and costly.
Several methods have been used to individually adjust the output intensity of lighting devices in lighting installations, but the methods are not practical for providing control over individual lighting devices that are part of an entire track or an entire floor of lighting devices. For incandescent lighting devices, individual electronic wall-mounted dimmer modules may be wired to each lighting device. Such a process may require twice the amount of wiring needed to simply provide power to the lighting device. Thus, in addition to the low efficacy and relatively short operational lifetime of an incandescent lighting device, connecting additional wiring to dim the incandescent lighting device adds hardware and labor costs to the overall lighting installation.
High efficacy lighting devices, such as metal halide lighting devices, typically cannot be dimmed effectively. Metal halide ballasts allow some types of metal halide devices to be dimmed but also require extensive wiring and control systems to enable dimming.
Other approaches to individually adjusting the output intensity of lighting devices include manufacturing incandescent light bulbs with multiple incandescent filaments, or installing neutral density filters within lighting devices. Incandescent light bulbs having multiple incandescent filaments typically require connection to a multiple-position switch in order to select one or more of the filaments within the lighting device. Similar to the approach using a wall-mounted dimmer, connecting additional wiring to support use of a multiple-position switch adds hardware and labor costs to the lighting installation. Additionally, installing filters to adjust the output intensity of the lighting device wastes energy by reducing the efficacy of the lighting device and suffers from the drawbacks associated with having a person physically elevated to the lighting device to adjust the output intensity of the lighting device.